My take - 120 volt linear controller

[diode663]

Hey guys,

Some of you may have seen my thread in the boiler section about my boiler build where I promised to post my controller setup.

Background: I live in an antiquated apartment building with no joke, 9 outlets total. One of these behind my fridge is fed by a dedicated 20 amp fuse. The fuse panel is fed by a single phase 30 amp fuse. With this in mind I do not have a lot of power to play with so I am stuck with 120 volts 20 amps as my limit. This allows me to run a 2000 watt HWD element in my 5 gallon 1/6th barrel still. This also pretty much limits me to stillin in the cooler months because I cannot get away with two air conditioners and my still without blowing the fuse.

I wanted to design a controller that was very linear and could easily be upgraded to 240 volt service in the future. So off I went to do the research. The SSVR seemed like a cheap reasonable route, but it was not linear and that was a sticking point with me for reasons I cannot express. I then stumbled upon a Crydom MCPC1225A which checked my boxes for linearity but wasn't future proof being stuck with separate voltage ranges. The other problem was it was 96 bucks. So I was stuck for a little bit until I stumbled across Auber Instruments DSPR1. This one checked all the boxes, it was linear, able to use 120 or 240, it had a nice digital readout with adjustment right on the unit, it could use off the shelf zero crossing SSRs and it was 33 bucks. Perfect. So begins the build.

Parts list:

Auber Instruments DSPR1 - Controller
Auber Instruments HS25ET - External 25 amp Heatsink
Auber Instruments MGR-1D4825 - 25 Amp Zero- Cross SSR
Auber Instruments SW6 - E- Stop
BUD Industries NBF-32018 - Great cheap enclosure found on amazon
3 Position terminal block
Fork connectors
wire
cable glands
wire loom
hold downs
zip ties

Pictures:

Parts from Auber

Front panel

Inside

Door Detail

Box Detail

Interesting Feature

Everything went together quite nicely. It works a treat. Some of you may notice that I did not connect the LED and left it out of the list. I got the led to give me a better visual of when the unit is sending power to the element. It turns out that the numbers on the controller do not light up if the output is not on making the LED useless. I was going to connect it to the E stop switch to let me know when it has been activated but that isn't really useful, so for now it sits unused. The e- stop breaks contact to the SSR to cease heating. I installed two plastic handles to protect the controller in the event it lands face down for whatever reason. The last picture shows an interesting feature. I do not know if this is on all Auber PID and controller products or if this is an industry standard but it is a great feature. If something happens to the controller you can just order up another one pop both of them out of the case and swap them out with no tools or the need to even open the box. Someone was thinking on that one.

So in the future when it comes time to upgrade all I have to do is change out the mains wiring, add a switch and a contactor to shut both legs off and I am good to go.

As always I welcome any comments or criticism. Thanks for looking guys.

[bellybuster]

That Auber unit is pretty nifty, surprised we haven't seen it here before. Not much more than the Chinese junk most of us have.
Although it's probably made in China too. Auber has a warranty though.

Great job on the controller, I'd still hook up the led just for fun, and maybe add in a siren too

[DeepSouth]

Very nice build. It's a PWM (Pulse Width Modulation) controller that you have there, and works great if the cycle time is set low enough. That Auber unit can have a cycle time as low as 1 second, and that is what you should use. 10% power means on for 0.1 s and off for 0.9 s. For our purposes, that kind of cycling won't be noticed by the liquid and your still should have no problems with surging. I built a similarly functioning controller using a 555 timer circuit with a potentiometer and various other capacitors and resistors to achieve a 1 second cycle time. Now that I see this Auber unit, I might want to replace mine because I don't have a digital display. I already have the SSR, box, and heat sink. Great build.

[diode663]

Thank you for the comments.

bellybuster- I will probably end up hooking the LED up to the e stop switch like you said just for fun. And I am most certain it is made in China. However since the unit comes apart I took a look at the circuit boards and solder joints and they are extremely well made, no blobs or cold joints or even crooked placed SMD components. And I really think that once people find out about this thing it will become the de facto standard replacement for an SSVR and a pot because it is pretty inexpensive at $33.

deepsouth- The cycle time for this unit is actually as low as you can go ( 1 ac cycle). This unit has two modes, the default burst fire mode as they call it and a time proportional mode like you are describing. The unit in its default mode which is perfect for SSRs has uses the smallest time base to achieve the desired duty cycle which can be as I said before 1 ac cycle or about 16 ms. This is more then fast enough for our purposes. The time proportional mode can be set as low as one second up to some number if you have a contactor or something but that doesn't really apply to what we do here. Check out their data sheet http://auberins.com/images/Manual/DSPR1%20manual_V1.pdf" onclick="window.open(this.href);return false;" rel="nofollow specifically the appendix section where it goes pretty deep into the operation of this unit.
I highly recommend this unit for price and functionality and as an upgrade if you have an SSR it will just drop right in. Also you can't beat a nice digital display.

Note that I do not work for Auber. I am just excited that I found something that was exactly what I wanted for a reasonable price.